Valve lifter



J y 6, 1954 c. vooRHlEs 2,682,865

VALVE LIFTER Filed May 8, 1952 4 Sheets-Sheet l 1 l :17' ff a 33 1 Mr f 34 W "a r 'l Z Y is x- 20w f E *26 `96 .fnyeiear July 6, 1954 c. vooRHlEs 2,682,865

VALVE LIFTER Filed May 8, 1952 4 Sheets-Sheet 2 @Elink-Qi.

July 6, 1954 C, VOQRHIES 2,682,865

VALVE LIFTER Filed May 8, 1952 4 sheets-sheet 3 jay/f 76 o 7),

T72 21672 for ffar/eeys July 6, 1954 c. vooRHlEs 2,682,865

` VALVE LIFTER Filed May 8, 1952 4 Sheets-Sheet 4 i fw 7 95 I 9 i valve retainer;

Figure 9'is'a plan view ofamodiiiedview of a Patented July 6, 18954 UNITED STATES FATEN T OFFICE VALVE LIFTER oari voonhies, Park Ridge, nr.. npplicafioniifay s, 1952, serial No. 286,846`

(ci. 128-90i invention relaties: to a: hydraulic tappet or' valve lifter.

IthasforA one obj-eet toi provdefar valv'eliifter of the hydraule type- Whieh means; arel providedl for' the prevention of' Io's`s, particularly during starting' o'onditiblfisof the erigir-ie in Whiclfi valve litters of the-type'sliovm areusedi Experience has shown that a solistantiall amount or check' valveitravel is advant'ageousV tof permit wide opening for starting Conditions. Whensucient vafve travel is' usedin the engine for" proper starting, an undesirable lift" loss may occur with enginei`n1'c`onneo'tionV` with which the cam shaft has beendesigned'v to operateat or near Izero' tappet' clearance.

Itis one-of thefobjeots of' the invention; therefore, to" provide `a` valve lifter so` arranged` that tli-islift loss is prevented byholding the check' valve-in thel valve lifter normally against the seat but/permitting a-wide opening lforlling the' f high-pressure' chamberin'f'a valve tappet during starting of trie1 engine.

Another ob'jectis to prevent lift loss proportional to-v the Volume* displacement;

Aotherobjects)Winl appear fiom viniera time-in the-course of' the speci'cation and'r claims.

granunatic'al-ly the accompanying drawings; wherein: f V

the valvelfte'r position ating rod in section;

Figure- 2' is 'a lifter;`v

with-'fthe valvepp'er- Figure ZiYis--al section taken at il`inev3"'-3'of4 f Figure 5'- is`V a perspective view off-the valve'- retainer removed fron'r its position inv the' assemlly; i y

Figure isfaA View generally,` similarto Figures 2i' and-4' illustrating a further modified; form in' Whichfmodicationsinthe plunger body and' in' the springarrangement havebeen made;

Figure 'T is-a perspective' View illustrating a spring Washerj removedfrom" theassembly;

Figure Siis a perspectiveview' of a modified check valve spring;y Y

Figure 10 ist atransverse' section taken alt' line in'ed form' of dieV device* in' whicn tite' invention longitudinali section ofVV the valve;Y

. into theT tappet` body and plunger; As shown; Il

is embodied not in the tapp'et but in an adjuster" positioned away from' the cam;

Figure 12` is a plan" View of thede'viceA of Figure 11; and y Figure 13 is a side" elevation of the device of Figure 11v with partsf omitted and shown on a reduced scale. y

Figure 14 is a section similar to Figure` 6" but showing the parts in the innermost' position' in which the valve portionl 2W is in Contact with' the end 9of the body 8. I

Figure 15 is a side-"elevation with parts' in sec'-- tion showing the passage I sov arranged that' the' groove IT is lloelowtlie passage Twhen'tlie engine valve is in the' closed position' as' sfown in that figure.

Figure 16 is ai' View* similar to Figure 15 aridi illustrating tliefaot' tliat then passage T is below Like parte are VYindicated ty iikei figures throughoutthe specification and drawings. g

the form ofE Figures 1 tof?, inclusive', the device isadapted for the pressure. feed of' I'luid is a ,portion of an engine; Adjacent tnei engine is positionedzacamvsnaftzcarrying earns 3. The' engine and theicam snaftfand" the saine are illustraten diagrammatically as' theirjdetaus forrn no part' offthe'invention; Within; the engine' pora groove |54.

Figure-v2; the lineriis' providedwith a spacer o n" i'ts exterior al'idj'a" perforation orV passage l i isY formed inthe liner and'within' the groove; 5E A:

` mayle beveledr'or reducedasat' Iilaloo'utits'openV end. One ormorep'erforation'sli maybe'forined in' the body. 8 adja'oeztits uppie'rend. It is shouldered asv at IZ'Withirf its open end' to receive a retaining ringvls': It'i'sprovidedat its exteribrwith I5is a passage formed' through tlie body andpositioned within the' groove f4. The tapp'e body is` also provided with an internal groove 16. Y a

A" plunger" IT isN po'siitoed' forY sliding' move- .3 and is reduced as at I8, the reduced portion producing an external shoulder I9. A valve retainer 2c is positioned about the reduced portion IS and bears against the shoulder I9, as shown. A spring 2| is positioned about the reduced portion I8 and about the valve retainer 26 and bears upon a flange 22 of the valve retainer 26. The spring 2| also bears against the closed end 9 of the body 8.

Within the valve retainer is a valve 23 which is reduced as at 24. This valve is held against displacement by the inwardly turned flange 25 of the valve retainer 2B. This flange 25 is provided with one or more grooves or depressions 26, as is shown particularly in Figure 5. The clearance between the inward faces of the members 25 and the end of the reduced portion I8 of the valve plunger I1 is suicient to permit the valve 23 to be moved from contact with the outer end of the reduced portion I8. The tappet plunger I1 is formed on its exterior with a groove .|1' which may register with the groove I6 on the interior of the body 8. A perforational passage 21 pierces a wall of the plunger I1 and is more or less in line with the passages 6 and I5. A tappet cap member 28 is positioned within the open end of the plunger I1 and is provided with a hemispherical depression 29 in which the rounded member 30 of the rod 3| may be seated.

The dimensions of the grooves I6 in the cylindrical body 8 and the groove I1 in the plunger I1 are such that their widths are proportioned one to the other and both of them are proportioned to the total travel of the plunger I1 so that when the engine is stopped and the plunger moves down to where the check valve projection rests on the bottom 9 of the body that the bearing surfaces between the plunger and the bore of the body would be clean of any deposits so that during the sliding motion no part of the bearing surface would ride over a deposit permitting the plunger to remain free to return to its original operating position without riding over any exposed surfaces whether of the plunger or of the body. f

The use and operation of this invention are as follows:

Figures 2, 4, and 6 illustrate the valve lifter in the position in which the engine valves are closed. This is also true of the modified form of Figure 12. Referring to Figure 2, the spring 2| holds the tappet body 9 against the cam 3 and the plunger is urged upward to where all clearance is taken out of the valve train. Oil from the engine oil supply is fed through passage 1, 6 and I through 21 into the reservoir or oil supply chamber 34. When the high pressure chamber below the check valve 23 is filled with oil as the cam revolves and the tappet is lifted, the parts of the valve train are carried on the column of oil in the high pressure chamber. During the time the valve is lifted slight leakage occurs in the clearance between the plunger I1 and the body I8. When the valve closes the spring urges the plunger I1 and the body 8 apart, check valve 24 opens and permits oil to pass from the supply chamber 34 into the high pressure chamber to replenish the supply of oil with the face 9 against the cam 8 and the lash out of the valve train. At the beginning of the rise of the cam, the check valve is closed and the column of oil is trapped in the high pressure chamber.

The operation of the modified forms of the device shown in Figures 4, 6, and 12 is the same as that which is described in connection with the form of the device shown in Figure 2.

When the engine is stopped, a number of the engine valves are in the open position in which oase the lifter leaks down to the point where the valve 24 bottoms on the head 9 of the body 8. If now the engine is started, the spring 2| urges the plunger I1 and the body 8 apart. The check valve 24 opens wide to admit oilfrom reservoir 34 into the high pressure chamber.

The operation of the relatively flat check valve washer spring 53 or 63 is as follows:

It holds the check valve 24 normally in contact with the portion I8 of the plunger I1 and thus closes the passage through the reduced portion I8. It assists Venturi action which occurs between the face of the valve 24 and the projection I8 in closing the valve quickly so that in normal operation the clearance is held closer to zero and a more quiet valve gear results, yet the spring permits wide opening of the valve required as in starting.

In the modified form of the device shown in Figure 4 the construction is generally similar to that shown in the first three gures and described above. The device of this modified form is, however, arranged for use with gravity feed in which the fluid which finds its way into the interior of the valve lifter or tappet does so by gravity rather than by force feed. Thus parts of the assembly which are the same in both cases will not be re-described and carry the same reference numerals as used above.

The liner 4 of Figure 4 is the same as the liner of Figure 2 but it is not provided with the perforations 6. The tappet body 8 is the same as that described above and shown in Figure 2 but it is not provided with external or internal grooves with passages through it except the perforations II adjacent its open upper end. The plunger I1 is substantially the same as that shown in Figure 2 except that instead of being provided with an external groove 26 it is reduced adjacent its upper end as at 32 and it is provided With one or moreV perforations 33-33 by means of which communication is established between the reduced portion 32 and the interior of the plunger. It will be noticed thus that the plunger I1 is in each form provided with an interior chamber 34. In the case of Figure 2, uid reaches this chamber by pressure through the sides of the plunger and in the case of Figure 4, fluid reaches the interior of the plunger by gravity. The valve 23, the spring 2|, and the valve retainer are the same in both forms of the device and need not ybe re-described. The cap 35 on Figure 4 differs from the cap 28 of Figure 2. It is yprovided with a depression or seat 36 within which the rounded member 30 is positioned and a passage 31 leads from the depression or seat 36 to the interior of the plunger.

In the modified form of Figure 6 the tappet or valve lifter assembly appears. The form of the invention shown in that ligure comprises a body 38, generally cylindrical and provided with an end-closing member 3S. Two grooves 40 and 4| are provided in the exterior of the body 38 and a passage or perforation 42 leads from the lower groove 4| and an internal groove 43 formed within the body 38. The body 38 is shouldered as at 44 to receive a retaining ring 45.

Mounted for movement within the body 38 is a plunger 46 provided with a reduced portion 41 adjacent one end. The plunger 46 is provided With an internal bore or space 48. A valve easement:

492 isiarranged'i to 1 closeithes'open end lof the re-v duced' portion.; 41.; A .valves retainer: 50: similar toforfv identical 'with'. the valyeeretainers.; 20L-oir the earlierl guresf positioned; abouti thetreduced portionadlrandi abou the `valve A'Qanduhold's ythe latten against: displacement; Aaspring: 25|v is'fsimiilar: to; or; identical with thee: springll of the earlierflgures; Itfbeallsat oneen'd:v against the innerirfa'cei ofil the endyvall39- of'the bo dyer 38? and at:itszotherendbears'.- against aangerzfof the retainer 50. A spring washer or ring 53 is posi; tionedfwithinitheavaive retainer;Elli'andaboutzthe outer edge :ofth'e' vaflve'fllB. It:ise.held. againstdis'- placement byr theinturned'flangef of! the valve retain'errl y The openupperendfof theplungenfM is'l closed by'a .cap155f whichis' providedlwith :aflange i6 and a'` depression*` orl seat 5T within. which an operat' ing` rodsimil'arf to orrCOmparabIe' with the rod3fl of" the" earlier iguresf-vmay beireceived. A dual rat'e springzZl-*is used.'

In the form of"l1`gureY Fthe spring`21'l'is shown as ii'tting closely over the` retainerv 2F and' it is' also shown asI fittingclosely into` a; depression formed" in the upper surfacefof the memberl 92 The springA isfin effect snapped into thisdepression4 and isi snapped onto themember 'and: its tension is such thatv substantial friction' is createdat itspoints of'engagenient with thet'appetbody 8"and'theiretainerwhich isrelativel'y o tight upon thereduced'portion lof 'thelplunger |71 The springin this formbecauseofthis relatively tight' engagement' resists a relative rotary movement ofthe plunger and body.

The shape and dimensionsv of the member 2'4 orl the equivalent checl valve-` in the various forms of the device are such that the check val've may attimes bottom on the'inner face ofithe closure 9 of" the tappet body; This occursat times in the normal engine-cycle as pointed out below and it may occur at other times as'fa result of the action ofV hard-4 or4 resistant particles of foreign matter in the oil.' Iffany liard'particles or foreign matterflodge on the outer 'face ofrthe memberA I8 or luponthe cliecl-A Valve-l 2'3fin' line with the outer face of l the`VV member '|824 the check valve .will be held openjandthere will thusbea momentary failure ofv the tappet tooperate `properly. When this occursY the plilngerjbottoms onrthe'mern-be'r!! and is'pressed andbeatsv down on the dirt' sol lodged betweenthevalve 23- and the opposed face oftheme'mber Ilviuntirtliefdirt is bron-enfV up or so reduced inl thickness'tha'tthe check valve can again properlylclose: that occurs'the valve' resumes its normaloperation and the plimgerand thev entirelcamassembly-return to normaliandicorrect operation;

The device is generally arranged in its various forms to provide forI the' escape of'airA from the system. In operation some-'air is inevitably drawn into the system and lsincefit lisr readily com'- pressible, its presence is disadvantageousandiitis desirable to provide means for its discharge-or leakage away from: th'e interior-ofthe'hydraulic valve lifter or'lash'adjuster: Airent'eringthe bore of" the plunger may' escape upwardly and outwardly through the clearance between the plunger' wall I and the=closure member 2'8 of Figure 2101A 'its' equivalentpart-in the-other fig'- ures. Air'onitsfwaygto'theinteriorofthe plunger F may escapeV upwardly along the=clea-rance between the plungerl Tfandthe body. Should air' be carried"downwardly^into the high' compression space" belowr thel plunger; within thebodyV 8; it will? tend to returnl upwardly along thel clear'` 5 ance 1 betwleerr thea plunger. and; thel body; The valve 2.3zandiits-'seat arepositioned .well belowsthe point: of? contactzof; theA plunger; I with the body iand. thus air. which'. finds its :way into the-high compression space; tends.- to move`V upwardlyand toleals outwardly betweenthe plunger. and the bodyf rather"r than. to return into thef space- `3l# through4 the opening; between the check` valve 23andfits seat.

The modified valve retainer as shown in Figureif. is generally the same as thatfof Figure 5 exceptthati it. provides greater opening forv the passageo oil Yfrom the supply chamber intothe high pressure.

Thezretainer of Figure is-designated generally by the. number 58 and is provided with a flangee59`wl1ieh diiers from the-flange 25o-fthe retainer Zby. the absence of the members 26.' The-flange Sti corresponds generally to the flange 2'2. of the formof Figure 5. Cutsl or openings S1 arevformed in the sides of thefretainer of Figure 8 andi extendithrough asubstantial portion ofthe height of' themember: and'through the flange 601 They may terminate in enlarged portions-62 at their.- inner ends if desired.

Thercheck valve spring ofv Figures 9- and 10 y differsfrom that of Figure 7' bythefact that it is formedx'cn a single radius. The check valve spring of Figures 9 and 10 is designated byv the numeralV 63'. n

In the modiedform oflFiguresvll to 13 inclusive, the clearance or lash adjuster is positioned in the linkage between the rocker arm and the cam but is not embodied in the tappet. As shown particularly inFigure 13', a conventional tappet 64 maybe used andoperatesincontactwith the carri- 3: A push rod `5fisi engaged bythe tappet El andmoved by it'.

Theadjuster as shown in Figures 11 and 13 includesA a body 6'61 of generally cylindrical por:- tion which isrprov-ided-'with a hollow extension 61 within which is received the endv of theA push rodV 8:51 The manner in which the push rodV is engaged" with or connected to the body 6B is immaterial and? the two` members` may be connected for cooperation by any construction which is desiredl A-n imperforate partition member .63 closes'. the` bottomof lthe body 65:v

Positionedv within` the body 6.5i is a1 hollow plui'igeriid.-v` The plunger isheld against'displacement'fromithebody by a snap` ring. or other retaining-'member' lll; The plunger itself is prO- vidediwith a-cylindricalcavity TI whichis open lat its lower end as at l2.

' At its-l upper e'ndtlfieA plunger 'is closed in part-byja roundedmember or portion 13 through which a passage or opening legis positioned. The portion 73" oftheA plunger inV the particular formshownfin'Figure 1l received within a socket 'Eiin one end of aV rocker arm lit; Arockerarrn is-'carriedon' aA rockerv shaft4 'i'i which is hollow as'fat 78. Thev rocker,Vv arm is provided with a passageway'lin communicationwith the interior I3A ofthe-rocker'arm 17. byV meansy ofY a duct Si?. The" passage or duct 7S.. of. the rocker arm communicateswith ,the passage 'I4 of thecplunger, The'particular shapingY and contacting features of the'v plunger and rocker. arm, are immaterial and thesefeatures may be of many, constructions. It is sufficient for the purposesof 'this invention that the two. cooperatingmembers be SO-,shaped that'they may cooperate together adequatelyY to supply oilto the interiorlofvthe.plunger..

The arrangementof'the parts at. the lower or inner 'endofthe plungerin the form of Figures 11 and 13 is substantially the same as that of Figures 2, 4, and 6. In each case there is a relatively flat valve, a valve retainer, a main helical spring outside of the retainer and a relatively flat spring within the retainer. Although these parts will be re-described with the modified form, they are substantially the same as those shown in the figures just mentioned and their purpose and operation are substantially the same as those above described.

80 is a check valve provided with an outwardly or downwardly extending boss 8 I. It is positioned within a retainer 32 which may be of the form shown in Figure or of the form shown in Figure 8. The retainer case, the flange 83 which is seated against a shoulder 84 formed in the plunger 59, has also a flange 85 positioned to embrace the valve 86. A spring 63 like that shown in Figures 9 and 10 may be positioned within the retainer and between its flange 85 and the check valve 86. A spring of the type shown in Figure '7 might also be used and for some purposes which will be described below this relatively flat spring may be entirely omitted. A coiled spring 86 is positioned within the body 66. At one end it bears upon the member Se and at the other end it bears against the flange 83 of the retainer, which flange is seated against the shoulder 84 of the plunger 69.

In each of the several forms of the invention, except that of Figures 11, 12 and 13, the cylindrical plunger is provided with a wide open bore. At one end it is closed, by a cap 28, 35 or 55, in Figures 2, 4 and 6 respectively. These caps are not sufficiently tight in the plunger to be xed with respect to them. They are sufliciently loose, each in its respective bore, so that pressure on the inner face of the cap will not be eiective to raise the plunger in which the cap is seated. The caps may thus be said to be free with respect to 'the plunger in which they are seated. Several advantages flow from this construction.

Thus the clearance between the cap .and the plunger in which it is seated forms a controlled or restricted leakage to permit escape of air from the ytop portion of the supply chamber 34 or 48. The free nt of the cap in the plunger also permits a larger diameter for the chamber 34 or l48, since it may be bored from one end, in a simple operation, and the diameter of the bore 34 or 48 is thus limited only by the necessity for providing walls of the cylindrical plunger of sucient thickness to provide suici-ent strength for the operation of the device.

Another advantage resulting from the free mounting of the cap in the plunger is that the pressure exerted on the lower surface of the cap which results from any oil pressure generally in the oil chamber 34 or 46 is taken directly against the lower end of the push rod 30, 3l and does not act on the plunger I1. Thus the total force tending to operate the plunger I7 and the cylinder 8 in the outward direction is reduced by the amount of the pressure in the chamber 34 or 48 multiplied by the area in the lower face of the cap 2B, 35 or 55 and the force tending to move the plunger l1 outwardly in the cylindrical body 8, is the sum of the force exerted by the coil spring and the effect of the oil pressure beneath the plunger.

The effect of this oil pressure is reduced by the fact that 'the caps 28 and 35 and 55 are loose and it is reduced to the extent of the pressure multiplied by the exposed area of the plunger.

In the form of Figure 6 a counter-bore is formed in the upper end of the 'plunger 46. Pressure leaking between the cap and 'the inner face of the plunger 46 is exerted against the lower face of the flange 56. Therefore pressure within the space 48 is in the form of Figure 6 exerted not only against the inner surface of the cap within the plunger but it is exerted also upon the under-face of the flange 46 and thus further reduces the pressure on the plunger by the area of that part of the flange exposed by the counterbore.

In an internal combustion engine where -hydraulic adjustment of the Valve gears is used that pump up where the valves are held open by the hydraulic device occurs mainly und-er two circumstances, namely, in some engines where the valve gear flats over the nose of the cam, and the other where the valve bounce occurs at the instant of the valve closing, although either or both of these may be beyond the possible speed of the engine. I-t is sometimes advantageous to cut off the oil feed to the hydraulic device when the valve is -in the closed position, and sometimes more advantageous to cut off `the oil feed when the valve is in the open position, depending upon the acceleration and deceleration of the cam operating the valve gear. Therefore, in order to teach the art to others, I nd it necessary to disclose the type of oil feed which cuts off oil pressure in the lifted position 'of the Valve of Figure 1 and another View which shows the oil supply cut off in the closed position (Figure 6). It may be necessary'in some cases 'to cut olf the oil feed a't both the closing and open position of the engine valve and allow oil to enter the hydraulic device only at an intermediate position where the passage 6 and the groove I4 are so positioned that the groove I4 -is below the passage 6 when the engine valve is seated and the groov-e I4 is above the passage l when the engine valve is open. In -this case oil can enter the tappet body I5 only at a point between the open .and vclosed position of the engine valve. The valve closed Iposition is shown in Figure l5 and the valve open position is shown in Figure 16.

The condition shown in Figure 14 is that which occurs when 'the engine is stopped and the large valve is in the open position and the tappet has leaked down to the full extent of the plunger travel. In that condition, the plunger has bottomed and the check valve is supporting the load with the valve portion 24 bearing against the inner face of rthe portion 9 of the body B. A 'dual rate spring 2 I is used.

Starting noise is one of the problems connected with the use of hydraulic adjustment of valve gear. Therefore, there is disclosed in Figure 8 an alternate design of the valve retaining cage to provide v-ery ample opening for fluid to pass the valve to permit starting without undue noise in the valve gear (Figure 8) I claim:

1. In a hydraulic valve lifter, a cylindrical member closed a't one end, a hollow plunger slidelably mounted therein, the said plunger provided with an opening in its inner end, and with means to admit liquid to its interior, a check valve mounted to close said opening, said check valve being positioned at the inner end of said plunger in such manner as .to touch the bottom of the closed end of the cylindrical member when the said plunger is at the bottom of its inward travel with respect to said cylinder, and a retainer positioned on said plunger and about and beneath a portion of said check valve, a portion of said rate and said spring holding said valve retainer cage in operating position, and a washer spring positioned between said cage and said valve, and biased to close said valve.

12. In a hydraulic valve lifter, a hollow cylinder closed at one end, a plunger slidably mounted therein, a spring interposed between said plunger and said cylinder and biased to urge the plunger away from the closed end of the cylinder, said spring having a dual rate of action, means within the plunger deiining a passage to the area within said cylinder, and a check valve for said passage.

13. In a hydraulic valve lifter, a hollow cylinder closed at one end, a plunger mounted within said cylinder for relative reciprocation, yielding means interposed between said plunger and said cylinder and biased to urge the plunger away from the closed end of the cylinder, the plunger and the closed end of the cylinder defining between them a compression space, means within the plunger deiining a passage to said compression space, a check valve for said passage and a washer spring biased to move said check valve to seating position.

14. In a hydraulic valve lifter, a hollow cylinder closed at one end, a plunger mounted within said cylinder for relative reciprocation, the plunger and the closed end of the cylinder defining between them a compression space, means within the plunger dening a passage to said compression space, a check valve for said passage and a washer spring biased to move said check valve to seating position, and a spring positioned within said cylinder and biased to move 35 said plunger away from the closed end of said cylinder, said spring having a dual rate.

15. In a hydraulic valve lifter, a cylindrical member closed at one end, a hollow plunger slidably mounted therein, the said plunger provided with an opening in its inner end, and with means to admit liquid to its interior, a check valve mounted to close said opening, said check valve being positioned at the inner end of said plunger in such manner as to touch the bottom of the closed end of the cylindrical member when the said plunger is at the bottom of its inward travel with respect to said cylinder, and a retainer positioned on said plunger and about and beneath a portion of said check valve, a portion of said check valve shaped to extend beyond said retainer, and a coil spring positioned within said cylindrical member bearing against its closed end and bearingalso against said plunger, the portion of said retainer positioned beneath said check valve having an offset portion defining a passage beneath said check valve and retainer.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,109,815 Best Mar. 1, 1933 2,203,952 Eshbaugh June 11, 1940 2,645,215 Moser July 14, 1953 2,654,356 Oldberg Oct. 6, 1953 FOREIGN PATENTS Number Country Date 988,202 France Apr. 25, 1951 

